public class Account{public string Name { get; set; } = "summit";public int Age { get; set; } = 22;public IList<int> AgeList{get;set;} = new List<int> { 10,20,30,40,50 };}

public class Customer
{public string Name { get; }public Customer(string first, string last){Name = first + " " + last;}
}

Console.WriteLine($"年龄:{account.Age}  生日:{account.BirthDay.ToString("yyyy-MM-dd")}");
Console.WriteLine($"年龄:{account.Age}");
Console.WriteLine($"{(account.Age<=22?"小鲜肉":"老鲜肉")}");

using static System.Math;//注意这里不是命名空间哦Console.WriteLine($"之前的使用方式: {Math.Pow(4, 2)}");
Console.WriteLine($"导入后可直接使用方法: {Pow(4,2)}");

if (*** != null)
{//不为null的操作
}
return null;

var age = account.AgeList?[0].ToString();Console.WriteLine("{0}", (person.list?.Count ?? 0));

IDictionary<int, string> dict = new Dictionary<int, string>() {[1]="first",[2]="second"
};
foreach(var dic in dict)
{Console.WriteLine($"key: {dic.Key} value:{dic.Value}");
}output:
key: 1 value:first
key: 2 value:second

private static bool Log(Exception e)
{Console.WriteLine("log");return true;
}
static void TestExceptionFilter()
{try{Int32.Parse("s");}catch (Exception e) when (Log(e)){Console.WriteLine("catch");return;}
}当when()里面返回的值不为true,将持续抛出异常,不会执行catch里面的方法.

在对方法参数进行检查时经常这样写:
private static void Add(Account account)
{if (account == null)throw new ArgumentNullException("account");
}如果某天参数的名字被修改了,下面的字符串很容易漏掉忘记修改.
使用nameof表达式后,编译的时候编译器将检查到有修改后自动导航与重构(-_-! 不知道翻译的对不对)
private static void Add(Account account)
{if (account == null)throw new ArgumentNullException(nameof(account));
}

c#5.0里是不支持这么写.Resource res = null;
try
{res = await Resource.OpenAsync(…);       // You could do this.…
}
catch(ResourceException e)
{await Resource.LogAsync(res, e);         // Now you can do this …
}
finally
{if (res != null) await res.CloseAsync(); // … and this.
}

public string Name =>string.Format("姓名: {0}", "summit");public void Print() => Console.WriteLine(Name);

static int LambdaFunc(int x, int y) => x*y;public void Print() => Console.WriteLine(First + " " + Last);